Star-testing a Super-Takumar 50mm f/1.4 lens

 The 8-element Pentax Super-Takumar 50mm f/1.4 lens was manufactured between 1964-1966.  According to internet lore (likely accurate), Pentax pulled out all the stops to manufacture this lens and sold it at a loss in order to claim "King of the Hill" status.  It is venerated in the Pentax community.  My copy has a low serial number and was therefore probably manufactured near the beginning of that time window.

I chose to do these tests with the lens mounted on a micro-four thirds E-M5iii camera.  This was a wise choice, because the results show that the edge performance on a full-frame (35 mm, e.g. Sony A7iii) camera would likely be bad. (It is.  See the end of this post) FWIW, the K&F Concepts adapter easily allows infinity focus, confirmed with a Bahtinov mask, which is greatly appreciated.

Here are two images of the lens mounted on the camera:

 The following images illustrate the performance over a series of f-stops: 1.4, 2, 2.8, 4.  Wide open, this lens is useless (actually, horrible) for astrophotography.  On a micro-four-thirds sensor, it becomes usable only at f/2.8.  These images show the stars in the handle of the Big Dipper setting over the Bristol Head ridge line.  Based on star separations, the actual focal length of this lens is 51.2 mm.

f/1.4 (ugh. yes, focused with a Bahtinov mask)

 

f/2.0, getting better, but still bad

 

f/2.8, acceptable

f/4.0, best, but slow

Some more pics, all taken at f/2.8:

Sagittarius

 

Corona Borealis over Bristol Head

 

In the image above, the position of the recurrent nova TCrB (T Coronae Borealis) is circled. This nova has an assumed eruption period of 80 years, which would make the year 2026 the next expected date. So far, nothing.

 

Fomalhaut (Alpha Piscis Austrini) over the southern flank of Snowshoe Mountain.

 

Lyra.  The Ring Nebula (M57) is circled near the left edge.

Conclusion: This is not a good lens for astrophotography.  Back in the day (film photography with manual-focus lenses) it was generally known that most lenses performed best when stopped down two or three stops from wide open.  The results here illustrate that quite well. This lens was great in its time, but modern lenses with special-dispersion glass and aspherical elements are are far superior when used wide open.

 Finally, an image taken the same evening after the moon rose above the ridgeline of Snowshoe mountain.  Not the Takumar.  A Panasonic Leica 9mm, live-comp 1-hr exposure.

Leica 9mm @ f/2. 1-hr.

The sky was covered with thin clouds Thursday night, but some stars were showing through, so I managed to acquire a couple test shots with the Takumar on a Sony A7iii.  This camera has larger pixels and a thinner sensor stack.  It still looks bad wide open, with severe astigmatism in the corners.

 

Thursday night. Sony A7iii + Takumar 50mm @ f/1.4

 

Hunter's Moon +1

 The full Hunter's Moon occurred here on Sunday night, but the sky was not clear until Monday afternoon, after a mix of rain and snow in the morning.  I used an Astro-Tech AT80EDT refractor to capture the 98.6%-full Moon rising over Snowshoe Mountain on Monday evening and setting behind Bristol Head Tuesday morning.

 

Moonlit landscape Monday evening

The 1-hr exposure above was obtained with an E-M1iii camera and a 7Artisans 7.5mm f/2.8 fisheye lens.

 

Hunter's Moon setting Tuesday morning

It rained, and rained, and rained

 Clear skies have been in short supply lately, with record rainfall and widespread flooding in southern Colorado and northern New Mexico.  There was a brief reprieve yesterday, but now it is raining again.

Friday (23 Oct)

 This weather brings to mind a poem that we came across in a visitor log somewhere in the notoriously-rainy South Island of New Zealand back in 1990.  The author was anonymous.

Rain

It rained, and rained, and rained,
the average fall was well maintained.

And when the tracks were merely bogs,
It started raining cats and dogs.

After a drought of half an hour,
we had a most refreshing shower.

And then, most curious thing of all,
a gentle rain began to fall.

Next day but one was fairly dry,
save for one deluge from the sky,

which soaked our party to the skin,
and then, at last, -- the rain set in.

Anon 

(lightly edited).

(tracks = hiking trails)

(we = the wife and I.  She gets credit for transcribing it) 

Star photography with an old Russian lens

Just for fun, I tried some astrophotography with an old (1976) Soviet-era Russian lens.  The lens is the Industar-50-2, (ИНДУСТАР-50-2) an M42 screw-mount 50mm f/3.5 lens.  This lens is remarkably tiny, only 68 g (2.4 oz).  It is a 4-element 3-group Tessar design.

This lens was designed to cover the standard 35-mm film format (what is now called "full frame" with respect to digital cameras).  Some initial test shots with a Sony A7iii camera showed very strong corner distortions at f/3.5, so I instead switched to a smaller-sensor E-M5iii camera and shot at f/4.  Even so, star smearing is still evident in the corners of the frame. 

Here is an image of the lens mounted on the E-M5iii with an M42 adapter:

 The following images were obtained on Tuesday night under a bright waxing gibbous moon, so exposures were limited to 30 sec.  Measurements of star separations show that the lens has an actual focal length of 52.7 mm.  This is consistent with many so-called "50mm" lenses from the film era, which were often closer to 52mm as revealed in lab tests publshed by Modern Photography and Popular Photography magazines.

I used a Kase AstroBlast diffusion filter held in front of the lens.  The lens has a non-standard 35.5-mm filter thread, which is incompatible with my screw-in filters. 

 

Saturn rising over Snowshoe Mountain

Constellation Lyra.  Vega is the bright star.

part of Cassiopeia

The Little Dipper barely fits in the frame.  Polaris is near the right edge.

The Andromeda Galaxy (M31) near center. 

Pleiades rising

 These two images are from Oct 04 and 05, before a run of rainy weather.  The Pleiades star cluster, also known as Messier 45 (M45) was rising over Snowshoe Mountain in the early evening.  Red and green airglow adds color to the otherwise dark sky.

04 Oct. equipment: Sony A7iii + Rokinon AF 85mm f/1.4 II lens

05 Oct. Sony A7iii + Rokinon 75mm f/1.8 + Hoya Softon filter

Morning Milky Way and Zodiacal Light

 At 5 am on Friday morning the sky was clear and calm.  The sky brightness to the east was measured as 21.45 mpsas, which is pretty good.  Jupiter is rising in the east and Orion is already high in the southeast.

Zodiacal Light and the winter Milky Way over Snowshoe Mountain

 This image was taken with an Olympus 8mm f/1.8 fisheye lens.  On the left, Jupiter is embedded in the triangular glow of Zodiacal light, which continues to arc upward from left to right.  On the right, the winter Milky Way arcs upward from right to left past Sirius and Orion.  The ridge line of Snowshoe Mountain is silhouetted against green and red airglow.

 This vertical fisheye image extends up past the zenith and into the northwest sky, just catching the eastern end of Cassiopeia.

 This image was obtained with a Laowa 7.5mm f/2 rectilinear lens and a Hoya Sparkle-6 filter.

The Moon fades, the Milky Way reappears

 After several days of deluge the sky was clear on Thursday night and last night.  There is now a window of darkness between the end of astronomical twilight and the rising of the waning Harvest Moon.

The last-quarter Harvest Moon was captured sinking behind the trees on the Bristol Head ridgeline yesterday afternoon:

 Later that evening (Friday) the Milky Way was once again an impressive sight:

 This photo was obtained with an OM-5II camera and an Olympus 8mm f/1.8 fisheye lens.  A digital low-pass filter was applied in post processing to suppress the faint stars.  This is a fisheye lens, so the view extends from the southern horizon up past the zenith and into the northern sky.

The next two images are also fisheye views with similar processing. 

view to the northwest

 

view to the north east

Three objects of interest are circled in the image above.  The planet Saturn is visible on the right.  In the middle, the galaxies M31 (Andromeda Galaxy, top) and M33 (Triangulum Galaxy, lower) are circled.  The Andromeda Galaxy is easily visible to the unaided eye with a dark sky like last night.  At a distance of 2.5 Million light years (Mly), it is the farthest easily seen object with the naked eye.  The Triangulum Galaxy is slightly farther away at a distance fo 2.8 Mly.  At magnitude 5.8, it is theoretically visible to the unaided eye under extremely dark conditions.  I tried, but my aging eyes could not pick it out last night.  The sky was nicely dark at the end of the observing session, with a measured sqml value of 21.62 mpsas in the eastern sky.